iOS audio: fix session closing

Close audio session after audio unit is stopped.

Change-Id: I15aacd8ab4a9782500e70bb0476ca32460fc4a06

src/media/audio/coreaudio/ios/corelayer.mm

@@ -341,10 +341,10 @@ CoreLayer::startStream(AudioStreamType stream)
 void
 CoreLayer::destroyAudioLayer()
 {
-    [[AVAudioSession sharedInstance] setActive: false withOptions: AVAudioSessionSetActiveOptionNotifyOthersOnDeactivation error: nil];
     AudioOutputUnitStop(ioUnit_);
     AudioUnitUninitialize(ioUnit_);
     AudioComponentInstanceDispose(ioUnit_);
+    [[AVAudioSession sharedInstance] setActive: false withOptions: AVAudioSessionSetActiveOptionNotifyOthersOnDeactivation error: nil];
 }
 
 void